Refining mineral oil



June 8,1937.

'- M. H. TUTTLE 'REFINING MINERAL OIL Filed hov. 20; 19:53 4Sheets-Sheet 1 INVENTOR. 4 lVa/rdmHM/e MM f ATTORNEYS.

June 8, 1937. "Mn. TUTTLE 2,083,511

REFINING MINERAL on. v

W e 4 \MN a B Q -..0 5 I u l wMN m 2 Wmm m w WWW MM m N mw wn a .w i FINVEN TOR.

A TTORNEYS.

June '8, 1937.

M. H. TUTTLE I mum numann. p11.

4 Sheets-Sheet 3 Filed Nov. 20. 1933- R. W5 m n wr I. fflywA m.

QNN

June 8, 1937 MjH. TUTTLE REFm I-Ns MINERAL on.

Filed Nov. 20, 1955 4 Sheets-Sheet 4 Patented June 8, 1937 REFININGMINERAL oI L Malcolm H. Tuttle, New Rochelle, N. Y., assignor to Max B.Miller & 00., Inc., New York, N. Y., a corporation of Delaware IApplication November 20, 1933 Serial No. 698,746

6 Claims.

The present invention has to do with refining mineral oils by means ofsolvents.

This application is based upon subject-matter divided out of the presentinventors copending application Serial No. 623,483, filed July 20, 1932,and also relates to certain modifications of the examples disclosed inthat prior application.

Mineral oils consist principally of intimate mixtures of compounds ofcarbon and hydrogen in 10 varying proportions. Certain of thesecompounds are especially useful and suitable for lubricating oil, forinstance for internal combustion engines and will be referred to asparafllnic. The other compounds are useful for other purposes but un,--

desirable in lubricating oils and will be referred to as naphthenic.

The solubility of pure paraflinic oil compounds in certain solventsdiffersfrom the solubility of naphthenic oil compounds in those solventsand it has been proposed to utilize this selective action for separatinga mixture of parafflnic and naphthcnic oils, as exists in a mineral oil,into fractions. However, asolvent for naphthenic oil, such asnitrobenzene, which has a limited solvent power for pure parafliniccompounds, in the presence of naphthenic compounds forms a mixture inwhich the paraflinic compounds have a relatively high degree ofmiscibility or solubility. Further addition of solvent to themineral oilmixture to remove more of the naphthenic compounds carries additionalparafiinic material into solution so that an attempt to improve thepurity of the paraflinic compounds results in both a loss of paraiilnicmaterial and a contamination of the naphthenic compounds. -In otherwords the improvement in the quality of one type of compounds can onlybe obtained where a single type of solvent is employed, by a lowering ofthe quality of the other type and is accompanied by a loss in yield 'ofthe high quality compounds of the flrsttype.

In accordance with the present development the quality of each class ofconstituents, parafiinic or naphthenic, may be improved 'up to the'point of producing an excellent yield of practically'pure compounds ofeach type desired, without ail'ecting the quality of the other class;that is, additional naphthenic material may be removed from the mineraloil without loss of parafiinic' oil. It is preferred to employ twosolvents having a limited miscibility in each other, one of which is asolvent for the parafllnic compounds and the other for the naphthenic.

Through the present invention it becomes possibe to produce the finalextract of each type of oil in equilibrium with the solvent for theopposite type oil: 1. e., the final extract of'the naphthenic fractionis accomplished with fresh paraffinic solvent and the final extract ofthe paraflinic fraction is accomplished with fresh naphthenic solvent. p

A feature ofthe present invention resides in providing improvedapparatus to continuously counterfiow the solvents and feed the oil,which is to be treated, at an intermediate point where it is subjectedto the action of the counterfiow- 10 ing solvents. When theinitialseparation is made in equilibrium with the charged oil, thecomposition of each layer is governed to some extent by the compositionof the charged oil as well as by the ratio of solvents employed so thatthe par- 5 aflinic layer then contains an appreciable quantity ofnaphthenic material and the naphthenlc layer contains some paraflinicmaterial. The present invention provides for separating the oil to betreated and purifying both layers without loss'of 20 oil constituents. i

It is also possible to adapt the counterfiow principle to batchtreatment whereby the oil to be treated is brought into contact withboth solvents so that a division into naphthenic and paraffinic 25layers occurs.

In either the continuous or batch treatment, purification of theresulting fractions without loss of oil desired in that fraction may beaccomplished by washing the naphthenic layer, includ- 30 ing naphthenicsolvent and removed from the other layer, with the paraiiinlc solventand the paraflinic layer, including paraflinic solvent and removed fromthe first-mentioned layer, with naphthenic solvent,'and separatelyrecovering the 35 solvents from the washed layers to produce theparaifinic and naphthenic fractions. The relatively fresh solvents usedfor the final washings, together with the materials taken intosolution,may be used for washing less pure fractions at 40 points preceding thefinal washings. The extent of washing and the amounts of solventsemployed may varywith the quality of each type of oil desired and oil tobe treated.

The present development is especially useful with crude, or asphaltcontaining oils, or oils which have been topped (distilled) to removelow-boiling fractions such as gasoline and kero sene, but which stillcontain asphalts, although it is also useful in connection with othermineral 50 oils.

A feature of the invention resides in the provision of novel andimproved apparatus for the purposes indicated.

A further featureof the invention resides in p naphthenic solvent entersthe apparatus adjacent the provision of apparatus in which a given layermay be treated repeatedly with solvent for constituents which areimpurities in that layer. the solvent being fresher or stronger in eachsucceeding treatment, so'that eventually that layer is treated withsubstantially pure solvent adapted to remove or strip the remainingsmallamountsof impu ities from that layer.

Another feature resides in apparatus for in'- U timatelyf mixing upperand-lower layers from the'layer is passed to a preceding pcintand usedas the solvent forthe preceding extraction.

Another feature of the invention resides in the provision of an improvedapparatusin which a plurality of solvents for respective constituents ofthe oil fiow in counter-current relation, or in other words. so thatparaffinic solvent is introduced adjacent the end of the apparatus wherethe naphthenic oil is removed and so that the the end where theparafilnic oil ,is removed. Preferably the' apparatus is so constructedthat the oil is introduced into an extracting chamber intermediate theends of. the system and is separated into fractions which are advancedtowards opposite 'ends of the system,.while the solvents fiow from theends 'of the apparatus in countercurrent relation. v

In one specific form of apparatus in accordance with the invention thesolvents fiow through a tower, the parafilnic solvent rising anddissolving parafilnics to form an upper layer and the naphthenic solventsettling and dissolving naphthenics-to form a lower layer, thecountercurrent fiow taking place while the constituents are actually incontact with one another;

In another form of countercurrent method and apparatus in accordancewith the invention. .a lower layer from a succeeding chamber and anupper layer from a precedingwchamber, containing respective solvents,are intimately intermingled and then fed into a generally horizontalsettling chamber, near one end. and permitted to gradually settle outtoward the other end of the chamber and form therein an upper and alower layer. Particular advantages are secured with this type ofapparatus as will be hereinafter pointed out. v

A relatively specific feature of the invention resides in apparatus forcarrying out the extraction continuously in a series of separatechambers, although it will be understood either a single chamber ofconsiderable length or discontinuous batch type apparatus may beemployed within the broad principles of the invention.

Another feature of the invention resides in apparatus which accomplishesthe treatment of both layers simultaneously in a closed system, thesolvents being recovered and recirculated.

Other objects, featin'es and advantages of the invention will appearfrom the detailed description of the several illustrative embodimentsdescribed, although it will be understood that the invention in itsbroader aspects is not limited'to such embodiments. I I In thedrawingsin which like reference'characters indicate similar parts.

11g. 1 shows diagrammatically apparatusembodying .my' invention andwhereby my process perature' c'ontrolling and solvent recovery fea"--'Pig. 2 shows diagrammatically a modification of apparatus wherebycounterfiow of solventsxand extraction of parafilnic andnaphthenicfractions may be practiced, such apparatus including temareeffected, the apparatus shown in tmfi il'sure Jbeing adaptable to thesolvent recovery muted,- perature controlling features shown in Fig. 3shows diagrammatically apparatu's'fenfi I bodying my invention andwhereby my mayxbe practiced as a batch operation continuous features;

Fig. 4 is a diagrammatic view of another of apparatus in accordance withthe invention.

In the .practice of this invention, oil which is to be divided intofractions which are respectively more parafilnic and more naphthenlcthan the original oil is treated or extracted with a solvent havinggreater solvent power for naphthenic constituents than for parafiinicconstituents, while the oil is in thepresence of a solvent which has"greater solvent power for parafiinic than for naphthenic constituents.Usually the latter solvent comprises one or more hydrocarbons of theparafiin series, and it reduces the viscosityof the more parafiinicfraction and facilitatu a. more rapid and complete separation therefromb t-gravity of a solution of naphthenic constituents. Also, it isthought that'theadvantagesof' this invention are due in part to areplacement by the parafiinic solvent, which is'a parafiin of suchparafilnicconstituents of the oil as may be dissolved in the naphthenicsolvent, the parafiinic solvent being readily recoverable from the'more'naphthenic fraction, and thus facilitating more.

complete recovery of the parafiinic constituents of the oil in and'a's'the more paramnic fraction thereof. In the description herein ofapparatus embodying my invention, and whereby my process may bepracticed. all of. the above-mentioned are present, but it is to beunderstood that the separate use of the described features falls withinthe scope of this invention-although such feafeatures of this inventionand additional features tures co-operate when used together to producethe advantages of this invention.

Referring to Fig. 1, a counterfiow of paramnic solvent and naphthenicsolvent is maintained through contacting or extracting elements II andIi and the oil to be separated into fractions is introduced to thecounterfiowing solvents at an intermediate point Theoperation will bedescribed in connection with the use of nitro-benzene havingsulphur-dioxide absorbed therein as the naphthenic solvent and propaneasthe parafiinic solvent,.although it is to be understood that othersuitable solvents may be employed. Nitro-ben'zene from tank II, whichmay be initialiyfilledby make-up inlet ll, is passed bypump llthrough'plpe ll, pipe it, and cooler top of absorber 1., which may be ofanyconstruction, causing contact of the liquid with gas il, whichcontains refrigerant coil ll, into-"the therein. Sulphur-dioxide fromgas holder II. is

passed by pipe 2i through cooler 22- containing refrigerant coil 23, andpipe 24, to the bottom of V absorber it, from which the residual gas isvented by vent II or returned by pipe it and pump ll -7 pipe I5. Byopening valve 30 and closing valve 5 3|, the sulphur-dioxide absorptionapparatus and step may be eliminated. Then the naphthenic solvent passesthrough mixer 32, heat exchanger 33,-pipe 34, cooling coil 35, and pipe36, into the upper portion of extractor I I.

Propane contained in tanks 31 and 38 ispassed by pumps 39 and 40 throughpipe 4| to pipe 42; and propane in tank 43, which may be initiallyfilled by make-up inlet 44, is passed by pump 45 through pipe 46 to pipepasses through heat exchanger 41, pipe 48, heat exchanger 49, pipe 50,cooling coil SI, and pipe 52, to the lower portion of extractor I0.

Oil to be separated into fractions is passed from tank 53, which may besupplied by makeup inlet 54, by means of pump 55, pipe 56, mixer 51,heat exchanger 58, pipe 59, cooling coil 50, and pipe 6|, to the upperportion of extractor I0.

Contacting and extracting towers I0 and II are provided with any typeof'packing,62, such as 2 coke, bricks, or raschig rings, suitable forpermitting contact of the oil and the solvents; and they are maintainedcompletely filled with liquid. Pumps I4, 39, 40, 45, and 55 maintainsuch pressure within the extracting towers, and cooling coils 35, 5|,and 60 maintain liquids flowing to the towers I0 and II at suchtemperature that the liquids in the towers do not vaporize and are atsuch temperature that separation of a solution of morenaphthenicfraction from a solution of more paramnic fraction occurs.From the bottom 01 extractor II there is drawn by pump 63 a quantity 0!the heavy fraction separating out in extractor II, and possibly a partof the lighter layer separating out in extractor I0, depending,

upon the rate of operation of pump 62. Liquid so withdrawn comprisesnaphthenic constituents, naphthenic solvent, paraflinic constituents,and paraflinic solvent, andit is passed through pipe 64, heat exchanger58, and pipe 65, into pipe 55, and mixed in mixer 51 with the incomingoil to be separated. The oil tobe separated may contain wax and have amelting point between 85 F.

and 90 F. necessitating the use of a steam coil' 66 in tank 53 in orderthat-it may be in liquid form; butafter admixture with the liquidwithdrawn from the extractor by pump 63, the incoming oil may be chilledin cooling coil 60 to a temperature well below that at which the waxtherein solidifies, and then the wax solidifies in par- 55 ticlesseparate from each other and separate from the oil, leaving the oil freeto be acted upon by the selective solvents in-extractors I0 and II.

At the temperature maintained within extractors I0 and II, the solventshave limited mutual solubility, and separation into an upper layercomprising the more parafinic fraction dissolved in the paraflinicsolvent and containing some naphthenic solvent, and a lower layercomprising the more naphthenic fraction dissolved in 5 naphthenicsolvent and containing some parafflnic solvent, readily occurs. Theresulting upper layer passes from the top of extractor II throughpressure regulating valve 61 to evaporating tank 68 containing coolingcoils 35, 5| and 60. The

-, pressure in tank 68, and therefore the temperature therein, isregulated by withdrawing therefrom vapor of parafiinic solvent bycompressor 69, the output of the compressor passing through condenser 10into tank 43.

The more parafiinic fraction, partly freed of 42. Propane in pipe 42tractor In vaporizer I00, the heat of coil sulphur-dioxide, which passesby pipe II2 to paraifinic solvent, is passed from-tank 68 by pump H toseparator 12. Naphthenic constituents dissolved in naphthenic solventand collecting in 1 the bottom of separator 12 pass through heatexchanger 33, in which the temperature thereof is raised',.- and thenthey pass through pipe 13 into pipe- I5 and are mixed with incomingnaphthenic solvent in mixer 32. occurs because the temperature andconcentration of parafiinic solvent therein are both lower than in thetop of tower II. Thus, naphthenic constituents which areundesirable'ingredients, of

the more parafilnic fraction are eliminated there-' from; and the oiladded to the incoming naphthenic solvent in pipe I5 permits thereduction of the temperature thereto in cooling coil 35 to a temperaturewhich may be below the crystallization point-of the naphthenic solventwithout occurrence of such solidification or crystallization.

The upper layer in separator 12, comprising the more parafiinic fractionand solvents, passes through pipe 14, heat exchanger 41, vaporizer I5,

pipe 16, vaporizer 11, p'pe 18, pipe 16, vaporizer 19, pump 80, and pipe8|, to parafiinic run-down tank 82, from which it may be withdrawn bypipe 83. In heat exchanger 41, parafiinic solvent is cooled, Invaporizer 15, the heat supplied by coil 84 vaporizes paraflinic solvent,which passes by pipe 85 to liquefying condenser 86, from which liquidparaflinic solvent passes to tank 38. In vaporizer 11, heat supplied bycoil 89 drives oil The separation in tank 12 sulphur-dioxide gas, whichpassesby pipe 92 to gas holder 20. In vaporizer 19, heat supplied bycoil 94 vaporizes naphthenic solvent, which.

passes through condenser 95 to tank I2.

Tar collecting in the bottom-of extractor I0 and constituting the morenaphthenic fraction dissolved in naphthenic solvent and containing someparaflinicsolvent, is withdrawn from ex- I0 by pump 96 and passedthrough pipe 91, heat exchanger 49, vaporizer 98, ppe 99, vaporizer I00,pipe I'0I, pipe 99, vaporizer I02, pump I03, and pipe I04, to naphthenicrun-down tank I05, from which naphthenic oil or tar may be withdrawnthrough pipe I05. In heat exchanger 49, paraflinic solvent is cooledpreparatory to further cooling in coil 5I, and the extent of cooling ofparaflinic solvent may be regulated by adjustment of valve I01 in pipe50 and by-pass valve I08. In vaporizer 99, the heat of coil I09vaporizes parafiinic solvent, which passes to liquefying condenser H0and then to tank 31. III drives off pipe 92.

If sulphur-dioxide or an equivalent ingredient is not employed,Vaporizers 11 and I00 are eliminated by opening valves II4. In vaporizerI02, the heat of coil II5 vaporizes naphthenic solvent, which passes tocondenser II6 and then to tank I2.' Pumps 11 and 96 provide the pressurenecessary for condensing parafiinic solvent in condensers 86 and H0, and

the pressure on the fractions freed of propane" is released by valves II1, and vacuum pump H0 insures that naphthenic solvent will be vaporizedin Vaporizers 19 and I02 at a temperature which will not alter the sameor the oil incontact therewith.

In the extraction step in towers I0 and II, the continuous upward flowof paraiiinic solvent and the continuous downward flow of naphthenicsolvent, preferably at temperature at which the mutual solubility ofthose solvents is limited, carries upward paraflinic constituents of theoil and H3 and closing valves A apparatus naphthenic fraction carriesdownward naphthenic constituents of the oil. Just prior to flow ofparaflinic constituen'ts from the extracting step they are washed withnaphthenic solvent, and just prior to flow of naphthenic constituentsfromthe extracting washed with -p'araflinic solvent,

stituents of the oil which are solution of naphthenic constituents.Apparently parafllnic solvent entering by pipe 52 takes up naphthenicsolvent which is released near the top of the extracting towers becauseof the lower temperature there; and the released naphthenic solventmoves downward and takes up oil constituents, thus giving a circulationwithin the extracting towers which aids the freshly supplied naphthenicsolvent.

In Fig. 2, there is shown a modiflediorm of apparatus whereby thecounterflow of solvents f and contacting thereof with oil is effected,this being more suitable in the case of solvents having a smallerdiflerence of specific gravity than nitro-benzene and propane. Throughthe contacting or extracting tanks I25, I2I, I22, I22, I24 and vents ismaintained, and oil to be separated is introduced to such counterflow atan intermediate point thereof. Naphthenic solvent from tank I2 is passedby pump I4, pipe I25, mixer I21, heat exchanger I25, cooler I25, andmixer I24 of tank I25,'and then into that tank. From the bottom of tanksI25, I24, I22, I22 and I2l, naphthenic solvent passes by pipe I2I, pumpI22, pipe I22, and mixer I24, intothe next preceding tank. The steamsupplied'each pump I22 is regulated by' a valve I25 controlled by afloat I25, which floats upon a solution of naphthenic constituents butsinks in a solution of paraflinic-constituents. From the bottom of thefirst tank I25, the more dissolved in naphthenic solvent and containingsome paraiiinic solvent is withdrawn bylpump 252 to tank I25, from whichit may be withdrawn for recovery of solvents by pipe, I21. The steamsupply to pump 252 is controlled similarly to the steam supply to pumpsI22.

Paraiilnic solvent from tank pump 45 to mixer I24 of the 42 is passed byfirst tank I25.

Parafilnic solvent containing parafllnic oil con- -I4I, cooler I42, andmixer.

. recovery by means of pipe the top 0! each tank to the mixer I24 of thenext succeeding tank by means of pipe I25. In passing from tank I24 totank I25, the upper layer from tank I24 through heat exchanger I25 andthen into pipe I25 and is mixed in mixer I2'I with naphthenic solvent,and the mixture through heat exchanger I25, cooler I25, and mixer I24 oftank I25, and then into tank I25.

stituents passes from Oil to be separated passes from tank 52 throiiEhI45,- heat exchanger pump 55 and pipe 55 to mixer I24 into tank I22: andthe upper layer of tank I2I, in passing to the tank I22, passes throughheat exchanger MI and is mixed in mixer separated, and the oil tank I22with the upper layer of the lower layer of tank I22.

The more paraihnic fraction in solution in parafllnic solvent andcontaining some naphthenic solvent passes from the top of tank I25through pressiue-controlled valve I42 to tank I44, from which it may bewithdrawn iorsolvent to be separated enters tank I2I and ofpressure-controlled valve I42, liquefied solvents may-be employed; andthe evaporation of cooler I25 ratus shown in the construction that upperfore it is passed from the system.

I25, a counteriiow of 501- introduction of oil to I40 wlththe (ill to beI45. By adjustment solvents in tanks I25 and I44, oreither of the mayprovide refrigeration for cooling coil I45 in and cooling coil I41in'cooler I42.

-In operation, the relative rates the rate of the respective supplypumps thereoi! that the level of the dividing line between the upper andlower layers in contacting and separatin'g tanks I25 to I25 may beproperly maintained by pumps I22 and pump 252. I

The solvent recovery and temperature regulating features of theapparatus shown in Fig. 2 may be employed in connection with the appa-Fig. 1 for those purposes- It will be apparent that from the operationof shown in Fig. 2 the flow of the upper layer in eachtank toward theright causes layer to take up more and more paraiiinic-constituents oithe oil, and that it is thoroughly washed with naphthenic solventbe- It,will also be apparent that the lower layer in being passed through theseveral tanks toward the left in the of supply of oil 7 and solventswill be so regulated by controlling system. Such thorough washing priorto removal from the system displaces undesirably absorbed constituents;and the presence 0! added paraflin hydrocarbon increases the proportionof parafllns present and assists the iinal separation. As a' result,proper separation is obtained in the treatment of highly naphthenic oilsin connection with which separation could not be obtained by the mereuse of nitro-benzene alone, at least without the use oi benzene. In theconstruction'shown in Fig. 3, contacting, extracting, and separation areeffected in tank I55, which is provided with means for the be separated,naphthenic solvent, parailinic solvent, and certain naphthenic layersresulting from intermediate separating steps, as hereinafter described.Tank I55 is provided with means for eifecting circulation and agitationof the contents thereof, including pipe Oil may be supplied to tank I55from tank 52 by pump 55, which discharges the oil through valve I52 intopipe I51.

A heavier layer comprising more naphthenic constituents, naphthenicsolvent, and some paramnic solvent may be passed from tank I55 toevaporator I52 by closing valve I55, opening valve I52, and operatingpump I52 to pass that layer through valve I54, pipe I55, valve I55, andpipe I51. Volatile paraiiinic solvent'is removed-from the contents oftank I52 by passing through pipe I55, cooler I55, pipe I15, valve Ill,and pipe I12, to tank I12, in which paramnic solvent is collected andwhich may be initially supplied through pipe I14. Valve I1I controls therelease of pressure upon the contents of evaporator I52. By openingvalve I15, liquid solvent may be passedthrough pipe I15 on to bubbledecks I11 in evaporator I52 to assist in the separationoi the solventvapors an excesdve amount of nitro I5I containing valve I52, pumpI52,pipe I54, 7

I55, to which from the liquids. When removal of parafllnic solvent iscompleted, pressure on the evaporator is reduced to permit vaporizationof the naphthenic solvent at a temperature low'enough to avoidalteration of either the oil or the solvent. To this end, valve "I isclosed and valve I16 is gradually opened in pipe I19 leading to tankI60, in which naphthenic solvent is accumulated and which may beinitially filled by pipe I6I. During 10 the evaporation of naphthenicsolvent in tank I63, the contents thereof is heated by circulationthrough heater I02 by means of pump I64, liquid being withdrawn fromtank I63 by pipe I65 and returned thereto by pipe I66; and reducedpressure is maintained in tank I63 by means of compressor I61 connectedto tank I00 by pipe I66 and discharging by pipe I69 through cooler I90into separator I9I, from which naphthenic solvent flows by pipe I92containing valve I93 back to tank I60, and non-condensable vapors passby pipe I94 to compressor I95, which discharges into pipe I 6I Upperlayers containing .the more parafilnic fraction dissolved in paraflinicsolvent and con-' taining naphthenic solvent, which are formed andseparated in tank I50, may be passed to evaporator I96 by closing valveI66 and passing the layer through pipe. I65, valve I91. andpipe I96.Volatile solvent is recovered from the contents of evaporator I 96 bypassing through pipe I99, cooler 200, and pipe 20I, valve 202, and pipe203, to paraillnic solvent tank I13, the evaporation being controlled byvalve 202. As in evaporator I63, separation of liquid from vaporsisassisted by reflux liquid passed through valve I15 and pipe I16 tobubble decks I11. After completion of the separation of volatile solventfrom the contents of evaporator I 96, valve 202 is closed, and thepressure in evaporator I96 is reduced by opening valve 204 in pipe 20I,which leads to naphthenic solvent tank I60, in which reduced pressure ismaintained as above described. The volatile solvent under high pressurein pipe I6I passes through cooler 205 and pipe 206 to volatile solventtank I13. 7

Non-condensable gases in tank I13 may be vented by means of pipe 201containing valve 206. Paramnic solvent may be introduced into tank I50through pipe 209, valve 2I0, pipe 2, valve 2I2, pump I53, and pipes I54,I55, and I51, valve I52 being closed and valve I56 being open.Similarly, naphthenic solvent may be introduced to tank I50 by l isingthat solvent from tank I60 through pipe 2J3 and valve 2I4 to pipe 2I I.

The more naphthenic fraction, freed of solvents, is w'ithdrawn fromevaporator I63 through pipe 2I5 by pump 2I6 and passed to tank I05.

The more paraflinic fraction, freed of solvents, is withdrawn fromevaporator I96 through pipe 2" by pump 2I6 and passed to tank 62.

The coolers or condensers, I69, I90, 200, and 205, are cooled by watercoils 2I9.

In order to obtain the beneficial effects of counterflow of solventsduring the treatment of successive batches of oil to be separated, inthe apparatus shown in Fig. 3, partially treated or extracted heavierlayers produced in tank I50 in successive operations are held in aplurality of tanks, which may vary in number, but of which four areshown in Fig. 3, namely, tanks 220, 22I, 222, and 223, the contents ofthese tanks being held at the pressure existing in tank I13 by means ofpipe 224 leading from pipe 201 7 and connected to each of said tanks bya valve and the naphthenic 22I while the paraflinic layer is retained intank naphthenic layers As the result of the treatment of successivebatches of oil from tank .53, tank 223 will contain a heavy layer leastrich in naphthenic constituents, tank 222 will contain a layer richer innaphthenic, constituents, tank 22I will .contain a layer still richer innaphthenic constituents, and

tank 220 will contain thenic constituents.

Assuming that a lighter or paraflinic layer a layer very rich innaphformed in tank I50 after discontinuance of the circulation of thecontents of that tank has been transferred to evaporator I96 for theremoval of solvents, as above described, then the contents of tank 220will be transferred to tank I50, and there will also be transferred tothat tankfrom tank I13 the amount of parafiinic solvent necessary forthe treatment of a new batch of oil to be separated. Then the contentsof tank I50 is circulated by pump I53, as described,'and the necessarycooling of the circulating liquid is accomplished by adjustment of valveI59 and operationof compressor I60, as above described. Circulation isdiscontinued after sufilcient contacting of the ingredients of themixture has occurred, and there forms in tank I50 a heavy naphtheniclayer and a lighter parafiinic layer. The heavier layer is transferredto evaporator I63 for removal of solvents, as above described; and theparafllnic layer is retained in tank I50. Then the naphtheniccontents-of tank 22I is transferred to tank I50 and circulated by pumpI53, and during such circulation there is added to the contents of tankI50 by pump 'a-batch of oil to be separated. drawn from tank 53.Circulation is continued until the added oil is put into solution in thenaphthenic and parafiinio solvents'in tank I50; and upon cessationofcirculation, two., lay e rs form and the naphthenic layer istransferred to tank 220 and the paraflinic layer is retained in tankI50. It is. to be understood that cooling is maintained during eachcirculation, in the manner described.

Then the naphthenic contents of tank 222 is transferred to tank I50, andthe contents of tank I50 is again circulated and separated into layers,layer is transferred to tank I50. Then the contents of tank 223 issimilarly treated, the resultant naphthenic layer being transferred totank 222.

Then, the amount of naphthenic solvent necessary for the treatment of abatch of oil to be separated is transferred from tank I to tank I50, andthe resulting mixture is circulated and the resulting naphthenic layeris transferred to tank 223. During these operations there has beencompleted in evaporator I96 the removal,

of solvents from the more parafllnic fraction produced in the precedingcycle of operations, and the solvent-freed more parafllnic fraction soproduced is passed to tank 62. Accordingly, the parafiinic layerremaining in tank I50 after the transfer of the naphthenic layertherefrom to chamber 246 is withdrawn from near the bottom of thischamber through valve 262 and pipe-263,

2,088,611 proper or desired rate of flow. The flow oi'upper 7 It will beunderstood that the number of chambers may be varied, or that a layermay be passed into a chamber further along than the one next to thechamber from which thelayer is withdrawn: Y

The upper or paraiilnic layer. from end chamber '25l is withdrawnthroughvalve 260 and pipe Ni and treated as hereafter described for .removal ofsolvents, while the lower layer from and treated for removal ofsolvents.

The present apparatus is particularly adapted for handling a normallygaseous solvent, suchas propane, and maintaining it in a liquid statewithout the need for refrigerationor for the conduct of operations attemperatures at which wax in the oil'would precipitate. The apparatusprovides for maintaining the materials in each of the chambers 243-25|under adequate pressure, for instance, by pumping the oil and solventsinto the system under pressure and limiting the withdrawal of theparaflinic and naphthenic .layers to such a rate as to maintain thedesired pressure, which may vary considerably depending onthe solventemployed: 160 pounds per square inch is satisfactory for propane. Inorder to prevent vaporization of solvent in chamber 25!, the valve 260is preferably of any known back pressure type, arranged so that thedesired pressure is maintained in chamber 25| regardless; of thepressure in line (26L Extraction chambers 243-25i and the connectingpipes for circulating liquid are all maintained full of liquid, so thatthere will not be air spaces inwhich a solvent may volatilize to bringabout an ineflicient .operation or the need for unduly large apparatus.

At the same time, it has been found desirable to circulate liquids inthe chambers near the center of the apparatus, particularly chambers243, 244 and 241, at a considerably higher rate than the rate at whichthe final layers are withdrawn from, the end chambers. That is to say,where a relatively pure solvent, to constituents present in relativelysmall proportions in the liquid in an end'chainber, is contacted withsuch liquid, the constituents are readily stripped from the mixture bythe solvent liquid back into the same which is hungry for them. On theother hand,

where the oil is initially treated with solvents.

already containing substantial amounts of dissolved constituents, thecirculation of the liquids is advantageously much greater in order toprovide a more intimate contact between all portions of the liquids.Preferably, an equilibrium is established between the solvents anddissolved constituents in each chamber, the recirculation aiding inaccomplishing this.

The present apparatus provides for maintaining the desired circulationat various points, by employing a pump 25! for each of the extractionchambers from which a lower layer is withdrawn,

and by providing a valve 259 for controlling the rate of flow of eachpump. It has been found that advantageous results are secured where theliquid from the bottom of chamber 243 is pumped into the chamber 244 ata rate two to four times as fast as the rate at which layers arewithdrawn from the ends of the apparatus, although the invention in itsbroader aspects is not restricted to any particular rate ofrecirculation. If desired, it is possible to by-pass a portion of thechamber from which it was withdrawn in order to aid in maintaining thewhich is partial with fresh naphthenic solvent.

solvent removed from each treatment and con-. taining some non-lubricantconstituents is preflayer from each chamber is thus controlled bytherate at which pumps 25'! circulate fluids from. the bottom of thechambers, so that by adjusting the flow of thelower layers the flow ofupper layers is automatically controlled. The present apparatus is thuscapable of establishing condi-.

tions of equilibrium in eachof the given chambers so that with a givengrade of oil the conditionsof treatment and quality of the product maybe maintained substantially uniform.

The temperature may be around 60 F. in the chamber 243 and possiblyslightly higher in the end chambers Lowering the temperature in the endchambers may increase the recirculation slightly. It has been foundadvantageous to keep the temperatures throughout at such a degree as to'promote the immiscibility of the solvents, and coolers or heaters may beprovided if necessary for maintainingthe proper, determinable conditionsfor given solvents.

The present apparatus is particularly simple to construct and efficientto operate where a countercurrent flow of large volumes of liquid isrequired, and where the solvents are several times the amount of oilunder er'ally desirable. At the same time, the provisions for intimatemixing and subsequent settling in a generally horizontal concurrent flowin the individual chambers appears to produce a superior and more rapidseparation of the oil into-fractions distributed in the respectivesolvents. Es

treatment, as is genpecial advantages are secured by the construction ofthe apparatus in such manner that each 4 successive upper chamber 243 tolayer from the initial layer in the final layer in chamber 25l growsricher in paraflinic pcrtions of the oil, while Similarly, the lowerlayer passing from chamber,

243 to the preceding chamber 246 is counterflowed with respect tosolvent for the paramnic or lubricating oil constituents, so that thepractically fresh solvent in chamber 246 has to strip but relativelysmall amounts of paraiflnlc oil from materials from which most of theparaflinic oil has alreadybeen removed.

Excellent results may be secured by separating from the oil a parafiiniclayer which may contain some other constituents ofthe oil, treating thelower with a fluid including a naphthenic solvent, removing the solutionthus formed from the paraflinic layer, repeating the solvent treatmentand removal to produce successively a more pure layer, and ultimatelywashing the parafllnic oil The naphthenic erably employed as the fluidfor the next preceding treatment, where it will dissolve more of saidconstituents. It will thus be appreciated that as the parafilnic oilcontains less impurities the solvent for impurities is stronger in eachsucceeding step. At the same time, it will be appreciated that theparaflinic oil is dissolved in a paraflinic solvent which in each stageacts to dissolve parafiinic oil carried over by the naphthenic solventfrom another stage. There is thus a countercurrent flow in the sensethat the less the other constituents mixed with the more concentrated isthe naphthenic solvent; there is also a countercurrent flow in the senseg combustion en ines.

' c solvent and naphthenic solvent 7 flow in opposite directions to oneanother.

on the other hand, there is se from the stock alayer relatively rich innon-lubricant sconstituents and also containing some lubricants, whichlayer is treated with parafllnic solvent in a system operating upon theprinciples set forth in connection with the treatment or the para!-flnic traction. A

The separation may be promoted by adding waterto the crude oil in .theapparatus to reduce the solubility oi the upper layer in the lower lay ,Apparatus or the following character may ad- 7 l vantageously beemployed ior recovering the solvents from the extracted oil fractions.

The parafllnic oil, c solvent and some entrapped naphthenic solventdischarged irom chamber "I and passing valve 2" is carried by line "I.to a suitable evaporator ill in which only the paraflinic solvent isvaporized by heating the mixture to a suitable temperature, say 350 1''.where the solvent is propane. The vapor is carried by pipe ill tocondenser 21!, where and the liquefied solvent is passed nk will. Theliquid paraflinic a rate controlled by a valve ill operatlvely connected'to a float!" in the evaporator, and is cooled in cooler I'll to asuitable temperature, say 'l40 It, where cresylic acid is employed asnaphthenic solvent.- Upon passing the cooled mixture into a receiverIll, a substantial portion oi the naphthenic solvent forms a lowerlayer, in which some small be carried, while the balance of the naphthenic solvent c oil and the form anupp r be separated from the mist andmay be drawn oil .trom the bottom of the receiver Ill and passed intoline I by-steam pump 21!, controlled by valve will and float Ill,connected in any convenient manner so that the operation of the pumpiscontrolled by the level 01' naphthenic solvent in the receiver 21}.

' The upper layer irom receiver ill may be passed through line 202 intoan evaporator "I in which the liquid may be heated by high presout ofdirect contact with the liquid,

5 cs by means or a iractionating tower having a lower flash evaporatorportion in which the lighter fractions 0! the materials are vaporized,and an upperstripping deck portion, in which the non-paraflinic vaporsare condensed. the heat of condensation being employed-to aid in heatingthe mixture entering the flash section. Suitable arrangements may beemployed (or heat exchange between relatively hot and relatively coolmaterials atdesired points. in the solvent recovery system. Thenaphthenic solvent vapors' may be liquefied in condenser I and passed tostorage tank I" through line I". The parafllnic oil irom the evaporatoror'still It! may be passed through line 201 by steam pump 2 controlledby valve "I and float ill, and into tank I"; g

Thls'oil constitutes a highly superior lubricating oil which may beemployed, after dewaxing if it has not previously been dewaxed, forinternal without further treatment,

, able to subject pass into tank naphthenic oil irom the bottom orevaporator 8.!

layer. In this manner, a portion of the naphthenic solvent may I a .butsubstantiallwall o! the oil constituentsiwhlch In some, specialcases.however. it, may be ,desirthe oilto other treatment, for instance, forremoving speciiic impurities, which I may' occur in certain crudes..Such additional treatment, 1! desirable for any reason, will be isminimised where lubricating is produced in accordance with the presentinvention.

The naphthenic oil, naphthenic solvent, and some c solvent leavingchamber 2 under the control otvalve "Lpassee through line I" into anevaporator seam which'par ailinic solvent is volatilised; The 30!-vent-vapors pass through line iii intoa condenser III, where they areliquefied, and then ill. The naphthenic solvent and maybe assedthroughline I" into an evaporator IN. A valve "I controlled in anyconvenient manner by a float It. serves to regulate the newer naphthenicsolvent and oil from the bottom of evaporatortll.

In the evaporator l, which'iunctions-similarly tothe evaporator I, thenaphthenic solvent is driven oi! from the mixture and is condensed incondenser 1 and then passed through line Ills into storage tank I, whereit mingles with the naphthenic solvent removed from the 0 oil. Thenaphthenic oil or tar from the bottom oi the evaporator I is conveyed byline I and pump 8 into storage tank Ill Thepumplllmaybeasteampumpsimilarto-. pump 2 and may be similarly controlled by avalve Iii operativelyvconnected to float Ill.

A high yield of naphthenic oil, which may be more or less tarry,depending upon the crude treated, is thus recovered and is useiul formany In order to return the the receiver 213 into the solvent may bepumped into line 252, and-this steam pump may be controlled by aconstant flow controller lit, in order to supply the paraflinic solventto the extraction desirparaflinic solvent from extraction system. the bya steam pump lit 46 tinuous operation in the apparatus 0! Fig. 4.'I'heconstant flow controller may be of any known construction. In orderto make upior solvent losses, additional solvent may be led intoreceiver 213 irom any'suitable source of supply (not shown) f Thenaphthenic solvent from the receiver 2 is pumped by steam pump!!! intothe line I where it mingles with a naphthenic solvent from the receiver210. The pump III is, controlled by a constant flow controller "Iconnected so that it regulates the total flow oi naphthenic solvent intothe chamber 2. Additional naphthenic solvent may be supplied to'receiver 2" as required, from a source of supply (not shown).

The present apparatus nts a number of advantages, among which is itssimplicity of construction. Moreover, the construction is such that aneflicient and intimate mixture oi the oil constituents and solvents iseilective, while 'at the same time a rapid and eihcient separation ofthe liquids into layers is accomplished. Thus, a sharp separation isachieved between the constituents which are desired in the lubricatingoil traction, and the other constituents, so that not only is a highyield of lubricating oil procured,

are desirable in the lubricants are found in the lubricating oilfraction which, on the other hand, is substantially free of undesirableconstituents I.

where the oil is to be used for'lubricating an automobile engine. At thesame time, the apparatus is reasonably inexpensive to build.

Where the terms parafllnic solvent and naphthenic solvent are employedherein, they refer to thesolvent action rather than to the chemicalconstitution of the fluids employed as solvents. Moreover, while it isbelieved thatthe action of such fluids is really one of dissolving oilconstituents, the invention is not to be restricted to this theory ofoperation, for, it may be that the fluids simply carry along the oilconstituents by some action which may not be at present entirelyunderstood. Accordingly, the term solvents is employed with this thoughtin mind.

Where the term lubricating oil is employed it refers primarily to afraction suitable for use in internal combustion engines, although theterm is not intended to exclude oils with shades of difference in theirproperties. Moreover, the other constituents removed from; certain stockmay possess lubricating properties for certain purposes, but theseconstituents are, nevertheless, referred to herein at certain points asnon-lubricant constituents because they are much less desirable for theformer purposes.

It will beunderstood that wax may be removed from the products of thepresent process, either before commencement of the process, or at somesuitable point after the extraction and before or after the removal ofsolvents from the extracted oil fractions.

In the practice of this invention, the oils treated'will preferably beviscous oils, i. e., oils having a Saybolt universal viscosity ofupwards of 50 seconds at F., including distillates and residues andmixtures thereof. By treatment in accordance with this invention, oilshaving characteristics comparable to or better than the characteristicsof similar oils produced from Pennsylvania crude petroleum may bereadily produced from oils from almost any field, including particularlyMid-Continent and coastal fields, it being animportant feature of thisinvention that oils having such desirable characteristics can beproduced from oils having a high content of asphalt, in some cases sohigh that treatment thereof with a single solvent is impracticable.

In the production of oils in accordance with this invention, preliminaryacid treatment is not necessary, although such a step may be performed;and the acid treatment ultimately required is markedly milder and moreeconomical than acid treatment required to attain the same degree ofpurification without treatment in accordance withthis invention. Forexample, 011 treated in accordance with this invention may be brought todesired color bythe use of five to ten pounds of 98% sulphuric acid andfive per cent of palm clay;' whereas the attainment of the same degreeof purity without treatment in accordance with this invention requiresas much as fifty pounds of suchacid, and also a heavy treatment of clay,per barrel of oil.

Oils constituting the more paraflinic fraction obtained by the practiceof this invention are dewaxable by known methods to produce oil of anycommercially desirable A. S. T. M. pour test, the type of wax-removalemployed, 1. e., filter. pressingor bydiflerenceof specific gravity,beingso chosen as to be well suited to removal of the wax precipitatedby chilling. Moreover, -when the solvents employed in the treatment ofoil in accordance with this invention include sulphur dioxide, the upperlayer of the separation, con

taining oil,. naphthenic solvent, and paramnic solvent, is well adaptedto dewaxing processes, the sulphur dioxide acting to limit the waxremaining in solution after chilling and acting to preventcrystallization of the naphthenic solvent, relatively mild chilling toobtain oil of 0 F. pour test.

The solvents employed are preferably so chosen that their boiling rangesdo not overlap each other or overlap the boiling range of the oiltreated. Thus, a mixture of oil to be treated and parafiinic solvent isnot to be confused with crude oil containing both naphtha andlubricating oil and comprising constituents of gradually increasingboiling point. Preferably, the solvents are separable from one anotherand from the oil by distillation. In the practice of is a feature thatthe solvent having greater solvent power for naphthenic than forparafllnic constituen of the oil is employed in conjunction with anothersolvent for the oil which preferably has limited solvent power for thenaphthenic solvent. Thus, while preferred paraflinic solvents have beenidentified heretofore, there may also be used in conjunction with thenaphthenic solvent a solvent which has a higher final boiling point thanthe solvents mentioned or is less parafflnic in composition or is notwholly composed of hydrocarbons or is not possessed of as markedselectively for solvents'above mentioned.

While the foregoing description makes reference to the liquefying ormaintaining liquidity of solvents or the distillation or driving mi ofsolvents, by maintaining temperatures and pressures suitable to suchconditions or effects, and such temperature and pressure conditions arereadily ascertainabie by reference to handbooks or by-simple test, it isdesirable to maintain in the contacting or extracting steps, andpreferably throughout portions of the apparatus in which volatilesolvents are transferred or used in liquid form, a pressure much higherthan is necessary to maintain liquidity. For example, in the'contactingand extracting zones or elements of the apparatus pressures as high as160 pounds may be maintained in connection with the use of propane.Thus, in the apparatus referred to in the drawings, successful operationhas been efl'ected by maintaining the pressure in the neighborhood of160 pounds in the contacting or extracting elements. In Fig. 1, suchpressure may be maintained in towers l0 and H while tower I0 is at 75 F.and tower is at about 50 F., while the pressure in receiver 43 is aboutpounds, all pressures being gauge pressures unless otherwise specified.Wax-containing oil may be maintained at such "temperature as will insurecomplete fluidity thereof, e. g., 135 F. to F., prior to introductioninto the system. .Subatmospheric pressure may be maintained, with orwithout simultaneous use of neutral substances acting to increase vaporpressure ofthe solvents, for the purpose of effecting the driving off orevaporation of solvents without decomposition of the solvents or of theoil; for example, evaporation of nitro- (10 F.) being required thisinvention, it

parafiine hydrocarbons as are the benzene may be effected by maintainingin tank I of more naphthenic fraction be effected. at a temperatureconducive to layer formation at which the solvents have mutuallimitedsolubility. In connection with the use of propane withnitrobenzene, an effective separation temperature is between 25 F. and40 l t, for example, a temperature of 30 .1. may be maintained inseparator II. when propane is used in conjunction with benzaldehyde, anefl'ective 0 separation temperature is F. when use with nitrobenzenecontaining absorbed sulphurdioxide. an effective separation temperatureis 0 lit-10 F. When used with nitrotoluene, an effective separationtemperature is F. when 15 using aniline with Pennsylvania gasolinehaving an end point of 300 F., separation may be effected-attemperatures as high as 150 1?. When usingfuriural with that gasoline,separation may be effected in the neighborhood of 80 When using pyridinewith propane, F}. will effect separation. When using more volatilesolvents than those mentioned, suitable pressures I 'and temperaturesmay diifer from the foregoing temperatures and pressures, but they are25 readily ascertainable.

Procedure in accordance with this'invention produces a" fraction moreparaflinic than the ori al; oil and'whichds an oil having more'desirablecharacteristi'csthan theoriginal oil, and a fraction which-is morenaphthenic than the original oil and which contains the asphaltoccurring in the original oil and is an asphalt having valuablecommercial properties. The oil obtainedrepresents a substantiallygreater yield than the yield res'ulting friwm the mere use or anaphthenic solvent. and the oil possesses'equal or bettercharacteristics than an oil produced by the mere use 'of a naphthenicsolvent.

For the purpose of illustrating the effect and 40 results of procedurein accordance with 1 vention, various specific eramples are herein described, with the understanding that this invention is not in anyrespect limited thereto but is amplified thereby. i p

Employing as the oil to be treated a stock compriisng a residue obtainedfrom Santa Fe Springs California. crude oil and having thecharacteristics given below, that stock was sub-- jected to treatmentsas follows:

A. The stock was subjected to acid treatment in accordance with goodrefinery practice, using fifty pounds of 98% sulphuric acid per barrelof stock. and the resulting acid sludge (hereinafter referred to asasphaltum loss) was drawn off and the oil was treated with pound of palmclay per gallon by the so-called contact method. a

B. The stock. without acid treatment, was treatedin accordance with thisinvention with four pounds of propane per pound of stock and wasseparated into a more parafilnic fraction hereinafter referred to as theoil fraction and a more naphthenic fraction hereinafter referred to asasphalt and loss. The separation tem- 5 perature was 15F. under 120pounds pressure. C. Thestockwas treatedwiththree pounds of nitrobenzeneper pound of stock, but no separation was obtained'at any temperaturedown to 30 R, presumably Wokthe high asphalt content of the stock. a v fD. The stock was treated with 'one pound of nitrobenzene and twopoundsof propane per pound of stock. the-separation of the solution) ofmore naphthenic fraction being eifectedat 76 1!, and the separation ofthe more paratilnic this infraction being efiected at 35 2!, under 60pounds pressure.

E. The stock was treated with one pound of nitrobenzene and four poundsof propane per pound'of stock, the separation conditions being asdescribed in test D". I

F. The stock was treated with'two pounds of nitrobenzene and four poundsof propane per pound of stock, the separation conditions being as statedin test D.

G. The stock was treated with two pounds of nitrobenzene and two poundsof propane per as in test D". a

In order to compare the effect of treatment in accordance with thisinvention with other treatment. in connection with a less asphalticstock. tests were made with a stock of reduced asphaltic contentconsisting oi the oil resulting from test B, substantially freed ofasphalt by propane treatment. as iollows:

H. The stock of reduced asphalt content was treated with one pound ofnitrobenzene perpound of such stock, the separation temperature being 50F. 7 v

J. The stock of reduced, asphalt content was treated with one pound ofnitrobenzene and two pounds of propane per pound of such stock, theseparation of the more paraiiinic fraction being eifected at 35 1''.and; the separation of the naphthenic fraction being eil'ected at 75 F.

K. The stock of reduced asphalt content was treated'with one pound ofnitrobenzene and two pounds 'of petroleum ether per pound of such stock,the separation being effected at 50 F.

L. The stock of reduced asphalt content was treated with one pound ofnitrobenzene saturated with sulphur-dioxide at 45 F. and two pounds ofpetroleum ether per pound oi su'ch'stock, the separation being effectedat 0 F.

M. The stock of reduced asphaltlcontent was treated with two pounds ofnitrobenzene and four pounds of propane per pound of such stock. theseparation temperature being as stated in test .1.

An example of the treatment of an overhead distillate of Mid-Continentpetroleum, said dis-- tillate having a specific gravity of- 225 A. P.1., a flash point of 560 1''., a Saybolt universal viscosity of 153seconds at 210 F. and 1125 seconds at F., a viscosity gravity constantof .838, and a viscosity index of 64,is as follows: i

N. The Mid-Continent distillate was treated with one pound ofnitrobenzene and two pounds of Pennsylvania gasoline having an end pointof 300 7., the separation being eifected at 50 F.

In connection with these tests, there is given below values which arethe average of a number of values obtained by repetition of the tests,with respect to the stocktreated and the oil recovered;

as follows: 4

1. Percentage,

pound of stock, the separation conditions being 7 based uponthe stocktreated. a

yield of oil, this being the oil obtainedby acid treating and claytreating or the more'paramnic fraction freed of solvent.

2. Percentage. based upon the stock. of loss of acid-treated oil or morenaphthenic fraction freed of solvent.

- 3. A. P. I. gravity of the'resulting oil.

4. Saybolt universal viscosity at 130 F.

5. Saybolt universal viscosity at 210 1".

6. Flash point in degrees 1".

7. Fire test in degrees I".

8. Lovibond color, quarter inch cell.-

9. Conradson carbon.

10. Viscosity gravity constant. 11. Viscosity index. With respect to theasphalt or more naphthenic fraction, there are given below:- 5 12.Specific gravity. 8

13. Melting point. 14. Ductility. The average yields and characteristicsof products obtained in tests A" to 6", employing 10 Santa Fe Springsresiduum, and the characteristic of the charging stock, as-explainedabove, were as follows: I

15 Stock .4 B D E F G 1.100%.-- 30% 82.1% Notsiepa- 01.5% 70.5% 00.5%55.8%

IS on 2. 01% 17.0% do. 38.5% 20.5% 33.5%4s.2% a. 10.8 25.4 21.0 0 20.325.1 20.7 28.4 4.143o- 207 505 .45.--- 282 257 232 200 20 5.158- 72 80 m71 05 02 0. 445%--- 450 450 n 450 450 450 450 7. 505"- 510 510 do 510510 510 510 8. B1110 Dark Dark -00.--. 50 5o 45 30 8113611 green 0. 0.00.7 do 0.30 0.40 0.30 0.38 10. .831 .801 do .827 .834 .824 .813 25 11.4280 00 do .103 110 103 102 12. Notre- 1.074 "410---- 1.048 1.078 1.0721.040

covered 13. -410.-- 150 do. 113 141 1:17 105 14. .415..- Brittle -do.100+ 100+ 100+ 100+ 30 The average yields and characteristics ofproducts having a flash test of 450 F. and a fire test of 510 F.obtained in tests H and J to N, employ-- ing oil of lower asphaltcontent, and the characteristics of the charging stocks, as explainedabove, were as follows:

Stock 11 1 x L M Stock N While the foregoing specific examples ofcharging stocks and final products relate -to- Santa Fe residue, to suchresidue treated with propane for 5 the removal of asphalt, and to aMid-Continent distillate, it is to be understood that this inventionrelates to all oils having a viscosity upward of 50 seconds at 100 F.and containing both naphthenic and paraflinic constituents.

55 From the foregoing, it appears that by the practice of this inventionproducts of highly desirable characteristics are obtainable from oilsnot separable by the use alone of a practicable proportion of anaphthenic solvent and that this 3 invention yields products havingmarked superiority over products obtained by use of naphthenic solventalone. From the foregoing results, the effects of increasing anddecreasingthe proportion of the solvents to the oil and to each other isindicated suillciently to enable the operator to achieve the desiredresults; and it is demonstrated that the use of a parafilnic solvent asherein described results in marked increase of yield and markedimprovement of viscosity index.

7 In the practice of this invention, the proportions of solvents may beextensively varied and the above results indicate the'efl'ects of suchvariations and enable the operator to obtain whatever results he maydesire, and commercial con- 75 ditions will impose some limitation uponthose 8 heavy liquid fromone chamber to said first-named means,

proportions. Also, the operator may vary the duration of treatment andmay repeat the treatliquid mixture, a series of successive chambers inwhich the lower layer removed from the firstnamed chamber is treated,and a series of successive chambers in which the upper layer removedfrom the first-named chamber is treated, and means to cause an upperlayer to fiow from a chamber in the first-named series to a chamber inthe second-named series.

2. In 011 refining apparatus, a chamber adapted to eflect a preliminaryStratification of a liquid mixture, 2. series of successive chambers inwhich the lower layer removed from the firstnamed chamber is treated,and a series of successive chambers in which the upper layer removedfrom the first-named chamber is treated, and means to cause an upperlayer to flow from a chamber in the first-named series to a chamher inthe second-named series and to cause a lower layer to flow from achamber in the second-named series to a chamber in the flrstnamedseries.

3. In oil refining. apparatus, means comprising a plurality of chambersadapted to cause intermediate chamber, means for withdrawing therelatively light solvent and materials dissolved therein from near thetop of the secondnamed end chamber, means for withdrawingthe relativelyheavy solvent and materials dissolved therein near the bottom of thefirst-named end chamber, and means for pumping the relatively another.

4. In oil refining apparatus, means adapted to cause contact betweencounterflowing liquids,

means near the bottom of said first-named means for admitting arelatively lightlsolvent thereto, means at a higher point for admittinga relatively heavy solvent, means at a point intermediate the point ofadmission of said counterflowing liquids for admitting oil means, meansfor withdrawing the relatively light solvent and materials dissolvedtherein near the top of said'first-named means, means for withdrawingthe relatively heavy solvent and materials dissolved therein near thebottom of means for removing lighter solvent from the mixture withdrawnfrom near the top of the first-named means, meansfor cooling theremainder and separating heavy solvent therefrom, and means forreturning the separated heavy solvent and any oil contained therein tothe first-named means.

5. In oil refining apparatus of the character described, a series ofchambers, means to introduce a aolventintooneend chamber, means tointroduce a solvent into the other end chamber, means to introduce oilto be refined into an intermediate chamber, means to introduce materialcontaining solvent withdrawn from each of said end chambers into saidintermediate chamber, said intermediate chamber being constructed andarranged to enable the mixture to separate into layers, means to pumpthe lower layer from to first-named 12 4 said intermediate-chamber intoa chamber be-. tween said intermediate chamber and an end chamber, meansto causethe upper layer from said intermediate chamber to flow into achamber between said intermediate chamber and the other end chamber by adiflerentiai pressure,

means whereby alower layer may be withdrawn from an end chamber andwhereby an upper stantlaliy full of liquid;

layer may be withdrawn from the other end chamber at a combined ratesubstantially equal to the rateoi' feed of oil and solvents into the endchambers and intermediate chamber, wherebyallo'f said chambers may bemaintained sub- 6. Method of separating oil into raflinate and.extract-!ractions by means of solvents, which.

comprises-admitting a solvent for rafilnate type oi constituents presentin the oil into one end chamber of a series-o1 extraction chambers,admitting a solvent for extract type of constituents present in the oilintothe opposite end chamber, admitting the oil to be reflnedinto anintermediate chamber, passing mixtures containing said solvents intosaid intermediate chamber to cause the oil to separate intoraflinate andextract layers therein, passing the extract layer from said intermediatechamber into an adjacent chamber and toward the first-named end chamber,passing the rafllnate layer from said intermediate chamber into an.adjacent chamber substantiaily'higherrate 0! flow of oil and solventsbetween said intermediate chamber and said chambers thereadjacent, thanthe rate of withdrawal of rafllnate and extract iractions from the endchambers.

MA COLM H. TU'I'I'LE.

